Stormwater runoff is a major source of water pollution of lakes, rivers, and streams. Runoff from parking lots, construction sites, and agricultural areas contain sediment, oil, and other pollutants.
Stormwater treatment systems have been developed to remove pollutants from stormwater runoff. In one system, stormwater flows into an inlet conduit connected to a buried water quality separator that removes pollutants from the stormwater. Stormwater flows into one end of the separator and flows longitudinally along the length of the separator through a sediment chamber and an oil chamber and out the other end of the separator.
The known water quality separator includes an elongate tubular body that surrounds the sediment and oil chambers. The inlet conduit opens into one end of the body, and the stormwater flows through the body to a discharge conduit at the other end of the body. The flow area of the body is larger than the flow area of the inlet conduit. This enables the stormwater to flow through the sediment chamber and oil chamber slowly enough for the sediment to settle and for the floating pollutants to float to the top of the flow.
Although the known water quality separators work reasonably well, there is room for improvement. The sudden increase in flow area from the inlet conduit into the body causes turbulent flow as the stormwater enters the body. Sediment does not settle out of turbulent flow. The flow must expand and slow before becoming a non-turbulent or laminar flow that allows the solids to settle down into the bottom of the separator under the influence of gravity. The length of the upstream or expansion portion of the sediment chamber required to convert turbulent flow into laminar flow reduces the length of the sediment chamber available for laminar flow and settling of entrained solids and decreases the efficiency of the separator in removing solids from stormwater flowing through the separator.
Thus, there is a need for an improved stormwater separator with a sediment chamber having a longer sediment portion that more efficiently separates solids from stormwater runoff. An improved water separator should remove solids from stormwater more efficiently that conventional separators without increasing the overall length of the separator.